1. Field of the Invention
This invention relates in general to an adjustable support assembly, and in particular to a assembly having at least two degrees of freedom in which one handle will lock the assembly in a desired position.
2. Description of the Prior Art
The present invention is directed toward improvements to the support system disclosed in a patent commonly owned by the applicant, i.e., U.S. Pat. No. 4,564,164, issued to Allen et al. on Jan. 14, 1986. Allen et al. discloses an adjustable support system having three degrees of freedom that can be locked in a desired position by one handle. Allen et al. is herein incorporated by reference.
The support system of Allen et al. relies upon a compression head to adequately secure the first and second blocks together when the handle is tightened. It has been discovered that frequently the forces exerted by a patient's limb being supported by the system of Allen et al. are sufficient to overcome the coefficient of friction created between the first and second blocks thereby causing them to rotate relative to each other. This relative movement will vary in its severity depending upon the forces created by the limb being supported. Discomfort or further injury may result to the patient when such movement occurs.
When the threaded member supporting the compression head of Allen et al. is withdrawn slightly from the blocks, the slots expand and both rods can be moved to the desired position relative to the blocks. Also, in this position the blocks can be rotated relative to each other. Sometimes it is desirable to restrict the relative rotation of the blocks while adjusting the rods. Allen et al. does not provide this feature.
Also, certain situations make it desirable to retain one of the support rods in a fixed position when adjusting the other rod. Allen et al. requires that both rods be loosened even if only one needs adjusted. Consequently, when adjusting one rod the other may inadvertently move. Allen et al. does not provide for maintaining one of the rods in a fixed position while adjusting the other.
The device of Allen et al. is employed advantageously because of its simplistic construction and the flexibility it provides for supporting a patient's limb, or various other structures. Thus, it is desirable to retain these advantages while simultaneously assuring that any unintended relative rotation of the first and second blocks is substantially prevented. Providing the support system with means for maintaining one rod in a fixed position while adjusting the other rod is also beneficial.